This invention relates to an improved foil system which is capable of receiving energy from the flow of a fluid medium and efficiently transferring a portion of such energy to the structure on which such foil system is supported. More particularly, the invention is directed to an improved sail system for sailboats and the like, although it should be pointed out that the invention is not so limited but has utility to efficiently extract or divert dynamic forces generated from fluid flow conditions regardless of the medium of such fluid flow, i.e., whether it be wind, water current, etc. Other applications of the device other than operating a sail craft include power generation, irrigation, littoral deposits, agricultural anti-frost and drying air movement. However, inasmuch as the use of the improved fluid foil system of the present invention in connection with a sail craft is an easily understood and recognized example, it will be used hereinafter as the means by which the present invention will be described.
In the art of sail craft, constant effort through the years has been utilized to decrease the difficulties of accommodating varied wind strengths and to increase the freedom to maneuver sail craft despite wind direction and strength. Effort has also been made and continues towards extracting wind power and water power especially at low flow rates while retaining the ability to accommodate substantially higher velocities thereof.
Various attempts have also been made to utilize foils ranging from airplane wings to sail simulations of ancient Samoan craft, tilted to either side of a mast or the like in changing tacks and seeking an increasing stability by varying the lateral tilt angle so as to control the above indicated parameters. Each said system however introduces unmanageable difficult mechanical complications such as heavy structural stresses and large control forces as well as introducing unreasonably complicated manipulation or timing mechanisms in order to control such foils.
Some attempts to utilize tiltable foils in connection with sail craft include U.S. Pat. No. 2,170,914 to Rummler issued Aug. 29, 1939 which, although generally indicative of rigging concepts in this area, fails to present structural, aerodynamic or operational solutions of a feasible commercial nature. Other patents include U.S. Pat. No. 2,319,999 to Jennings issued May 25, 1943 directed to a wing flap control; U.S. Pat. No. 1,670,936 issued May 22, 1928 to McIntyre et al; U.S. Pat. No. 2,126,665 to Rowland issued Aug. 9, 1938 and directed to a complex system of multiple booms pivoting on the hull for sail support and operation; U.S. Pat. No. 2,387,907 to Hook issued Oct. 30, 1945 which includes a sail foil which can vary its lateral attitude; U.S. Pat. No. 4,177,345 issued Mar. 7, 1978 to Gurley directed to a sail supported by two spars directly mounted on a revolving mount located proximate to the hull and controlled through torsional means working on its shaft; U.S. Pat. No. 3,858,542 issued Jan. 7, 1975 to Lenoble directed to a hand supported foil; U.S. Pat. No. 3,924,870 issued Dec. 9, 1975 to Spivak et al and also directed to hand supported sail; U.S. Pat. No. 3,455,261 issued Jul. 15, 1969 to Perrin also directed to a foil structure having particular utility for a sail board; U.S. Pat. No. 2,329,220 issued Jul. 12, 1939 to Rummler directed to a variable spread sail/spar structure which is cumbersome and limiting, that is, utilizes a 45.degree. pivot in order to alternate the two sail support spars in horizontal and vertical positioning depending on which tack the vessel is on and thus causes the air flow to essentially flow normal to the vertical spar and parallel to the other; U.S. Pat. No. 2,106,432 issued Jan. 28, 1938 to McIntyre which is directed to a multi-hull craft, the hulls of which can be skewed relative to one another so as to align the wind loads on its two inclined sails relative to its two inclined centerboards. The above recitation and discussion of these patents and other prior structures constitutes applicant's Prior Art Statement; and in that regard, a copy of each such patent is enclosed herewith.
It also may be apparent from the above discussion that the underlying objectives of the present invention are not accomplished by presently available devices in the intended manner. Accordingly, a basic object of the present invention is to provide an improved fluid foil system which can be used to extract or divert substantial dynamic forces generated from fluid flow conditions in such a manner that such foil can be controlled adequately and simply by extremely light and straightforward structural means which can be provided at a reasonable cost.
An additional object of the present invention is the provision of a fluid foil system which operates in a greatly simplified manner and which, accordingly, reduces the learning effort and experience which an operator must acquire to operate the system and yet which has wide adaptability and usefulness when applied to water sail craft such as sailboats.
A further object of the present invention is the provision of an improved fluid foil system which can be used in fixed location power generating systems which is effective in very light winds or in slow water currents as well as in fluids of higher velocity and when assuming different flow directions.
These and other objects of the present invention are accomplished by a fluid foil system for imparting energy from a moving fluid medium to a supporting body, said system including a fluid foil connected to a mast along a longitudinal axis thereof, said foil supported for multi-rotational movement with respect to said body, said foil further adapted for lateral tilt in either direction with respect to said mast about said longitudinal axis from a rest or "level" position where said foil is free to be aligned with the directional flow of said fluid medium to a tilted position wherein said fluid imparts energy to said foil, and self-leveling means for said foil connected to both said foil and said mast and adapted to urge said foil to said rest position.
Other objects, features and advantages of the invention shall become apparent as the description thereof proceeds when considered in connection with the accompanying illustrative drawings.